The deadly coronavirus may have circulated in the United States as early as December, about a month earlier than believed by the US Centers for Disease Control and Prevention, according to researchers with UCLA.
원문출처 : https://www.cnn.com/2020/09/15/health/us-coronavirus-tuesday/index.html
원문출처 : https://www.cnn.com/2020/09/15/health/us-coronavirus-tuesday/index.html